Just choose any file that starts with @SuppressWarnings("nullness") and eliminate the annotation and fix the errors!

As of 2020-07-20 setting -Xmaxerrs 10000 there are 1451 errors in the core Java SDK.

Imported from Jira BEAM-10496. Original Jira may contain additional context.
Reported by: kenn.
Subtask of issue #20497